Several of Iraq's top religious leaders have denounced Sunday's deadly bombings of five Christian churches in Baghdad and the northern city of Mosul. Iraqi government officials say those who attacked the churches were trying to drive a wedge between Christians and Muslims. Meanwhile, a videotape posted on the internet shows the apparent killing a Turkish hostage.

Iraq's most respected Shiite spiritual leader, Grand Ayatollah Ali al-Sistani, has condemned Sunday's church bombings as "terrible crimes." He issued a statement calling on all Iraqis to unite against those who would kill them and destroy their houses of worship, regardless of their religion.

The interim government's national security advisor, Mouffaq al-Rubaie, told the Reuters news agency that the church bombings "bears the blueprint" of Jordanian militant Abu Musab al-Zarqawi, who has been linked to al-Qaida.

In an interview with VOA, interior ministry spokesman Sabah Kadhim refused to confirm the link to Mr. al-Zarqawi himself, but he said the church bombings and similar attacks do bear the hallmarks of al-Qaida.

"We have no real evidence of that. To be fair, I don't think it's a question of just a person like Zarqawi, wherever he is or whoever he is, really conducting all this," said Mr. Kadhim. "To me, I think the facts are there were training camps in Afghanistan and therefore there are fully trained terrorists from throughout the Middle East, who are misled to believe that there is this fight between Christianity and Islam."

Four Christian churches in Baghdad and one in Mosul were car bombed on Sunday evening as many worshippers were at prayers. It is the first time the Christian minority in Iraq has been targeted in such a coordinated way, although there have been a number of attacks on Christian-owned liquor stores.

Meanwhile, a videotape has surfaced on the internet appearing to show the execution of a Turkish hostage being held in Iraq. The man is believed to be an employee of a Turkish catering firm, although it is not clear when he was kidnapped or killed.

The videotape shows the man urging Turkish citizens not to work in Iraq. He is then shot several times.

Abu Musab al-Zarqawi's group, Tawhid and Jihad, has threatened to kill two other Turkish hostages, both of them truck drivers abducted last week.

In Ankara, the Turkish International Truckers' Association announced Monday it would stop carrying goods to coalition forces in Iraq as a result of the kidnappings.

More than 70 foreigners in Iraq have been kidnapped over the last several months.